Maciek,
My particular installation doesn't have gdal compiled with Grass support
(yet), so I need another work around, hence r.mapcalc/patch.
~ Eric.
-----Original Message-----
From: Maciek Sieczka
To: Patton, Eric
Cc: grassuser@grass.itc.it; grass-dev@grass.itc.it
Sent: 5/11/2006 2:52 PM
Subject: Re: [GRASS-dev] More efficient to use r.mapcalc or r.patch in a
loop for creating mosaics?
On Thu, 11 May 2006 14:16:32 -0300
"Patton, Eric" <epatton@nrcan.gc.ca> wrote:
I'm writing a script to mosaic an arbitrary number of rasters
together. So far, the script works fine, using the following mapcalc
statement in a 'for' loop:r.mapcalc "$OUTPUT=if(isnull(Map_A), Map_B, Map_A)"
I should note that I'm reading the map names in through an array
which was populated in a previous step. My question is: Is there an
advantage in using r.mapcalc over using r.patch for this work? At 1m
resolution rasters, and about 60+ of them, this could take a long
time.
How about GDAL?
gdal_translate to create an empty raster, of the target extents
write your maps into it with gdalwarp one by one
It should be faster than Grass.
There's also gdal_merge.py but it consumes lots of memory and may fail.
Maciek
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